Review of Nervous System PDF

**Review + Vocab** What parts of neurons make up gray matter? - The central body of the neurons (soma) and the dendrites that are attached to the soma - Basal Ganglia: Gray matter deep in the cerebrum What part of neurons make up white matter? What is this structure wrapped with? - It...

**Review + Vocab** What parts of neurons make up gray matter? - The central body of the neurons (soma) and the dendrites that are attached to the soma - Basal Ganglia: Gray matter deep in the cerebrum What part of neurons make up white matter? What is this structure wrapped with? - It is found in the axon of neurons - It has myeline sheath - They are covered in "myeline" which insulates, speeds, and protects - REMEMBER: "Node Of Raviner" Is NON-Myelinated Part Of AXON Does gray matter or white matter conduct action potential faster? Why? - White matter conducts faster action potential due to the "myelinated sheaths in axon" - These sheaths are thicker and meant to " insulate, speed, and protect What do astrocytes and ependymal cells do? - Astrocytes Cells - Found in CNS - Controls chemical environment - Forms blood barrier - Most abundant, versatile, highly branched glial cells - Clings to neurons, synaptic endings, and capillaries - Support and brace neurons - Helps determine capillary permeability - Guide migration of young neurons - Participate in info processing - Ependymal Cells - Separates fluid in cavities - Ranges in shape from squamous and columnar - May be ciliated - Lined central cavities of brain and spinal column - Separated CNS interstitial fluid from CSF in cavities. Define the following: Neurons, Nucleus, region. Which is the "house", Neighborhood/City", and the "State"? - Neuron: Individual Cell (House) - The CNS consists of Neurons (the functional units\_ and neuroglia (supporting cells) - Nucleus: Collection of neurons (City) - A cluster of neuron cell bodies in CNS is called a nucleus, while a similar cluster in PNS is called ganglion - Region: Collection of nuclei (State) **Protection** What structure protect the CNS? - The "Meninges" protect the brain - Protects and covers the entire CNS and forms partitions within CNS - Protects the blood vessels and encloses sinuses - Contains Cerebral Spinal Fluid (CSF) What are the Meninges? List the three layers from deep to superficial and describe a defining feature of each. 1. Dura Mater - The "Tough Mother" consists of 2 dense irregular connective tissue layers - Periosteal layer: Attached to bone - Meningeal layer: Forms dural fold (falx cerebi, tentorium, cerebelli) that prevent brain rotation and twisting 2. Arachnoid Mater - The "Spidery Mother", a web like middle layer that contains CSF 3. Pia Mater - The "Tender Mother", a thin layer that adheres directly to the brain surface Which layer of the meninges creates compartments of the brain? Can you list three major extensions that create these compartments? - Found in Dura Mater 1. Falx cerebi - Sickle shaped folds that separate the left and right cerebral hemispheres 2. Tentorium cerebelli - A crescent shaped fold that separates the occipital lobes from the cerebellum 3. Falx cerebelli - A smaller fold separated the left and right cerebellar hemispheres What is brain herniation? What can it be caused by? - Part of brain is squeezed, squishes, or forces across structure (fall cerebra, tentorium cerebella, foramen magnum) within the skull. - Caused by increased in intracranial pressure **Ventricles and Cerebrospinal Fluid** What are the functions of CSF? - Is filtrate of plasma, fluid filtered out of capillary, thru pia mater, thru ependymal cells, and into the ventricle. 1. Buoyancy - Reduces brains weight, prevents crushing under its own weight 2. Protection - Cushions brain and spinal cord from shocks/impacts 3. Nutrient delivery - Transports nutrients, ions, and solutes to neural tissues 4. Waste Removal - Picks up waste and returns it to venous circulation via arachnoid villi. 5. Chemical Stability - Maintains a stable environnement for proper neuronal function What structure produces CSF? Which neuroglia cell is a key component of this structure? - The "choroid plexus" is the tissue that produces CSF. - The key neuroglia cell is Ependymal cells. - The choroid plexus is made up ependymal cells, pia mater, and capillaries What are ventricles? - Four interconnected cavities in the brain where CSF is produced and flows - Lined by ependymal cells Describe the flow of CSF through the CNS. Include the ventricles, structure, and space CSF flows through. 1. Lateral Ventricles - CSF is produced in the lateral ventricles 2. Interventricular Foramina - CSF flows from the lateral ventricles into the third ventricle 3. Third Ventricle - CFS passes through the third ventricle 4. Cerebral Aqueduct - CSF travels form the third ventricle to the fourth via this narrow passage 5. Fourth Ventricle - CSF flows into: - The central canal of the spinal cord - The subarachnoid space vis the media and lateral apertures 6. Subarachnoid Space - CSF circulates around the brain and spinal cord, providing protection 7. Arachnoid Villi - CSF exists the subarachnoid space through arachnoid villi, entering venous sinuses and returning to systemic circulation CSF is constantly being produced (about 0.5 L/day) and flows around and throughout the brain. What is the purpose of the blood brain barrier (BBB)? Which neuroglia cells is a key component of the barrier? - The BBB protected the brain from pathogens, toxins, and harmful substances - Prevents large, charged, and/or water-soluble substances from entering brain tissue while allowing essential molecules like glucose, oxygen, water, and lipid soluble substances (CO2, alcohol, caffeine, nicotine, anesthetics) to pass. - The key neuroglia is Astrocytes - Their perivascular feet surround brain capillaries and contribute to the formation of the BBB Selectively permeable barrier that separates systemic blood from the brain **Cerebral Cortex** What are gyri and sulci? What is the benefit of increased surface area in the cerebral cortex? - Gyri - Ridges/ elevated folds on the cerebral cortex - Sulci - Grooves/ indentations between the gyri Together they give the brain its wrinkled look - Benefits: - More neurons: - supports higher cognitive function (reasoning, memory, language) - Enhanced connectivity: - More surface area for synaptic connections between neurons, supporting complex processing and integration of information - Compact design: - Fits within the skull while maximizing functionality Include the following lobes: frontal, parietal, temporal, occipital What are the major functions of each lobe? Include the central sulcus and transverse cerebral fissure (extra: where is the longitudinal fissure located) Include the precentral gyrus and postcentral gyrus What do these gyri control? Include Broca's area and Wernicke's area What does each area control? A diagram of the brain Description automatically generated Frontal Lobe - Major functions: - Motor control - The frontal lobe is primarily responsible for voluntary motor function, particularly in the "precentral gyrus" - Cognitive functions - This includes planning, reasoning, problem solving, and decision making - Speech production: - It contains "Broca's area", which is crucial for speech production and articulation - Precentral Gyrus - Located just in front of the central sulcus, the precentral gyrus controls voluntary motor movements in the opposite side of the body (Movement of limbs and facial muscles) - Broca's area - Typically located in the left hemisphere in the posterior part of the frontal lobe (specifically in the inferior frontal gyrus). It is responsible for the production of speech, including the formation of speech sounds and ability to speak. Parietal Lobe - Major functions - Sensory processing - The parietal lobe processes sensory input to touch, temperature, and pain forms the body. This function is mapped on the postcentral gyrus. - Spatial awareness and navigation - The parietal lobe is also involved in spatial orientation and body positioning. - Attention and coordination - It helps with the coordination of movement and sensory processing integration - Postcentral Gyrus - Located just behind the central sulcus, the postcentral gyrus ins the primary somatosensory cortex, responsible for processing tactile sensations (ex, touch, pain, temperature) from the body. Temporal lobe - Major Functions: - Auditory processing - The temporal lobe processes sounds and involves in hearing and interpreting speech - Memory - It plays a key role in memory function. As it houses the hippocampus - Language comprehension - The left temporal lobe includes the Wernicke's area, which is important for understanding spoken and written language - Wernicke's area - Located in the left temporal lobe (typically in the posterior part of the superior temporal gyrus), Wernicke's area is involved in language comprehension, both in understanding spoken and written words. Damage to this area results in Wernicke's aphasia, where individuals may produce speech that in fluent but nonsensical. Occipital Lobe - Major Function - Visual Processing - The occipital lobe is primarily responsible for processing visual information. It interprets signals form the eyes and processing features like color, movement, and depth perception Sulci and Fissures - Central Sulcus - The central sulcus, located between the frontal and parietal lobes, divides the motor (frontal lobe) and sensory (parietal lobe) areas of the brain - Transverse Cerebral Fissure - This fissure separates the cerebral hemispheres from the cerebellum, located under the occipital lobe. - Longitudinal Fissure - This deep groove divides the brain into two hemispheres (left and right), running along the midline of the brain. What are the three functional areas of the cerebral cortex? 1. Motor Areas - Controls voluntary movements - Ex. Precentral gyrus (primary motor cortex) In the frontal lobe 2. Sensory areas - Process sensory input (touch, temp, pain) - Ex. Postcentral Gyrus (primary somatosensory Cortx) in the parietal lobe 3. Association Areas - Integrates and interprets sensory and motor information - Responsible for higher functions like learning, memory, reasoning, and language comprehension - Ex. Broca's Area (speech production) and Wernicke's area (language comprehension) What are the three motor areas of the cerebral cortex? Where are they located and what do they control? 1. Primary motor cortex - Location: precentral gyrus of the frontal lobe - Function: Controls voluntary movement of skeletal muscles - Long axons of corticospinal tracts - Large pyramidal cells of precentral gyri 2. Premotor cortex - Location: Anterior to the primary motor cortex (precentral gyrus) in the frontal lobe - Function: Plans and coordinated learned or repetitive motor skills (ex. Typing and playing an instrument) - Involved in planning of movement that depend on sensory feedback 3. Broca's Area - Location: Frontal lobe, in Left hemisphere. Anterior to inferior region of premotor area. - Function: Controls muscles involved in speech production. Is active as one prepares to speak. What are the 5 sensory areas of the cerebral cortex? Where are they located and what do they control? 1. Primary Visual Cortex - Location: Posterior aspect of the occipital lobe - Function: Processes visual information received from the retinas, such as shapes, colors, and motion 2. Primary Auditory Cortex - Location: Temporal lobe, near the ears - Function: Interprets auditory information, including pitch, volume, timing, and spatial location of sounds 3. Primary Olfactory Cortex - Location: Inferior and medial region of the temporal lobe (visible from a midsagittal view) - Function: Responsible for the perception and recognition of odors, receiving input from the olfactory bulb and tracts 4. Primary Gustatory Cortex - Location: Deep within the lateral sulcus - Function: Interprets taste information, such as intensity and flavors (ex. Sweet, salty, sour, bitter, and umami) 5. Primary Somatosensory Cortex - Location: Postcentral gyrus of the parietal lobe, directly posterior to the central sulcus - Function: Processes sensory input from the skin, skeletal muscles, joints, and viscera, enabling spatial awareness and tactile discrimination What are the functions of the multimodal association area? 1. Integration of sensory Information - Combines input from multiple sensory areas (visual, auditory, somatosensory) to create a complete perception. - Ex. Recognizing an object using sight, touch, and sound 2. Complex thought processes - Supports reasoning, problem-solving, and abstract, thinking by synthesizing different types of information/ - Ex. Interpreting visual and auditory cues during a conversation 3. Decision Making and Planning - Evaluates current situation and pat experiences to make decisions and plan actions. - Ex. Choosing a path based on recognition of landmarks 4. Language and communication - Integrates auditory, visual, and memory areas for language interpretation, and production - (Receives input from multiple sensory areas) - (Sends outputs to multiple areas, including premotor cortex) - (Allows us to give meaning to info received, store it as memory, compare it to past, decide on action to take) Describe the three parts of the multimodal association areas. Which ones are involved in intellect, pattern recognition, and emotional capacities? 1. Anterior association area (prefrontal cortex) - Location: Frontal Lobe - Function: - Intellect, learning, and cognition - Personality, judgment, and planning - Decision making and reasoning - Development depends on feedback from social environment 2. Posterior Association Area - Location: Large region of parietal, temporal, and occipital lobes - Functions: - Plays role in recognizing patterns and localizing us in space - Involved in understanding written and spoken words (Wernicke's area) 3. Limbic Association Area - Location: Medial temporal lobe and parts of limbic system - Function: - Emotional responses - Memory formation - Linking emotions to experiences - Part of the limbic system - Provides emotional impact that helps establish memories **White Matter and Deep Gray Matter** What are the three central white matter tracts? What parts of the brain does each one control? 1. Association Tract - Function: Connect different regions with the same hemisphere (Connect gray matter within the same hemisphere) - Control: Communication between cortical areas in the same hemisphere - Ex. Linking sensory areas with motor areas (don't get confused. It is linking in the same hemisphere) 2. Commissural Tract - Function: Connect corresponding region in the two hemispheres (connects gray matter of right and left hemispheres) - Communication between left and right hemispheres - Ex. Corpus callosum is the largest commissural tract 3. Projection Tracts - Function: Connects the cerebral cortex with the lower brain regions and the spinal cord - Control: Relay motor commands from the cortex to the body and sensory input from the body to the cortex. - Ex. Internal capsule carries motor signal to the spinal cord What is the basal ganglia made of white matter or gray matter and what does the basal ganglia control? - The Basal Ganglia is made out of gray matter - Gray matter deep in the cerebrum within tracts of white matter - Helps control voluntary motor movements (in conjugation with primary motor cortex), procedural learning, routine behaviors or habits, emotion, etc. What type of muscles does the basal ganglia have input on? - It has an input mainly on skeletal muscles - It regulates voluntary skeletal muscle movements, ensuring they are smooth and coordinates - It works indirectly by influencing motor pathways through the thalamus and connections to the primary motor cortex - It also helps suppress inappropriate or involuntary movements of skeletal muscles What are the Caudate nucleus and Nucleus Accumbens responsible for? In what conditions would you expect them to be altered in? - Caudate Nucleus - Sensory/Motor function - Motor control (regulates voluntary movement) - Habit formation, learning, and memory - Controls goal directed actions - Altered in (slideshow: Schizophrenia, OCD): - Parkinsons disease (movement issues due to dopamine loss) - Huntington Disease (Involuntary movement, Chorea) - OCD/ADHD (Difficulty with planning and habit control) - Nucleus Accumbens - Central to the reward system (motivates behavior, pleasure) - Regulates dopamine release - Important for reinforcement and processing reward-related cues - Altered In (Drug addiction): - Addiction (substance or behavioral) - Depression and anxiety disorders (affects motivation and mood) - Schizophrenia (altered reward processing) What is the hippocampus responsible for? - Memory formation - Critical for converting short term memories into longer term storage - Spatial Navigation - Helps with orientation and understanding the environment. - Learning - Supports the learning process by associating experiences with emotional responses Altering In: - Alzheimer's (memory loss and cognitive decline) - Depression (shrinkage of the hippocampus, linked to impaired memory and mood regulation) - PTSD (affects memory processing and emotional regulation) How do the left and right hemispheres of the brain differ in their function and what is the significance of cerebral lateralization? Cerebral lateralization - Each Hemisphere - Receives sensory information from the opposite side of the body (contralateral) - Controls motor for the opposite side of the body - Lateralization of Cortical Functions - Refers to the division of labor between the two hemispheres of the brain Right hemispheres - Function - Insight - Visual spatial skills - Intuition - Artistic abilities Left Hemisphere - Function - Language - Math - Logic "split -- brain" Experiments (Roger Sperry 1961) - Cutting the corpus callosum in patients with epilepsy - Gained insight into the distinct function of the left and right hemisphere **Diencephalon** Where is the epithalamus located? What part of a ventricle does it form? What foes the pineal gland produce? What does it induce? - Located above the thalamus - Forms the dorsal part of the diencephalon - Contributes to the roof of the third ventricle - Pineal Gland - Produces melatonin -- induces sleepiness What is the function of the thalamus? - Relay inform to cortex: Sorts, edits, and relays sensory info (except small) from spinal cord to proper part of cortex - Motor Control: Relays motor signals form cerebellum and basal ganglia to motor cortex. - Two egg shaped clusters of cell bodies (nuclei), one on each side of the third ventricle What is the hypothalamus? - Located under the thalamus, on each side of the third ventricle - It is part of the diencephalon and plays a key role in homeostasis What functions does the hypothalamus regulate? - Fight or flight, sex, eating, and stress - Hemostatic functions - Reproduction and sex drive - Water and food intake - Temperature regulation - Stress response - Endocrine control - Regulates activity of the anterior pituitary via the infundibulum - Releases hormones through the posterior pituitary lobe What is the function of the suprachiasmatic nucleus? What would happen in the SCN was removes? - Suprachiasmatic Nucleus (SCN) - Regulates circadian rhythm (sleep wake cycle, daily biological processes) - Acts as the master clock, syncing the body's internal clock with external cues (light/dark). Adjusted daily by light form eyes. - SCN controls secretion of melatonin by pineal gland - If SCN was gone - Disruption of circadian rhythms - Loss of natural sleep wake cycle - Irregular sleep patterns and other physiological issues **Brainstem** What does Brainstem do? - Controls automatic behaviors necessary for survival - Contains fiber tract connecting higher and lower neural centers - Associated with 10 of 12 cranial nerves What are the three parts of the brain stem? Midbrain - Located between the diencephalon and the pons - Corpora quadrigeminal: - Superior colliculi (vision reflexes). Helps process visual stimuli and coordinate rapid eye movement. - inferior colliculi (Hearing reflexes). Help mediate auditory reflexes, such as turning the head in response to sound. - Cerebral aqueduct: Transports CSF from the third to the fourth ventricles - Cerebral peduncles: Contain corticospinal tracts for motor control - Substantial nigra: Involved in movement control, and damaged in Parkinsons disease Pons - Building like pillow structure - Fibers connect higher brain centers and spinal cord - Relay impulses between motor cortex and cerebellum - Nuclei maintain breathing - Composed mainly of white matter tracts connecting the cerebrum and cerebellum and spinal cords. Medulla Oblongata - Autonomic reflex centers - Vomiting, hiccupping, swallowing, coughing, sneezing - Respiratory centers - Cardiovascular centers - Joins spinal cord at formen magnum - Forma part of 4^th^ ventricle wall and contains choroid plexus - Pyramids : 2 ventricles longitudinal ridges formed by pyramidal tracts - Decussation of pyramids: Crossover of corticospinal tracts What happens to the substantia nigra in Parkinson's disease? What is the result? Substantia Nigra (Normal function) - Located in the midbrain - Contains dopaminergic neurons (produce dopamine) - Neurons project to basal ganglia via the nigrostriatal tract - Helps control movement and coordination Parkinson Disease - Degeneration of dopaminergic neurons in the substantia nigra - Leads to lack of dopamine production - Disrupts communication between substantia nigra and basal ganglia - Results in movement problems: tremors, stiffness, slow movement (bradykinesia), and balance issues Postmortem differences - Normal brain: Dark substantia nigra (healthy dopamine producing neurons) - Parkinsons brain: Light substantia nigra (loss of dopamine producing neurons) What is decussation? Where does it occur? - Definition: The crossing over of nerve fibers from one side of the body to the opposite side - Founds in the medulla oblongata at the pyramids - Motor fibers in the corticospinal tract cross over - Right brain controls left body and left brain controls right body due to this crossover **Cerebellum** What is the cerebellum? - 11% if brain mass - Dorsal to pons, medulla, and 4^th^ ventricle - Provide precise timing and patterns of skeletal muscle - Recognizes and predicts sequence of events during complex movements - Play role in nonmotor functions like words associations and puzzle solving What is the function of the cerebellum? Cerebellum controls: - Rate, range, direction, and speed of movement - Coordination of fine tunes motor activates - Posture and balance What are the three tracts the link the cerebellum with the brain stem? Cerebellar Peduncles: 1. Superior Cerebellar Peduncles - Connects the cerebellum with the midbrain 2. Middles Cerebellar Peduncles - Connects the with the pons 3. Inferior Cerebellar Peduncles - Connects the cerebellar with the medulla oblongata and spinal cord **High mental functions** What disorders help us learn about language centers in the brain? - Aphasias: Speech and language disorder caused by brain damage - Help identify and understand language areas like the Broca's area and Wernicke's area. What is the difference between Broca's area and Wernicke's area? Result of both aphasias? - Broca's Area: - Necessary for speech production - Damage causes Broca's aphasia, leading to difficulty in speaking, but comprehension remain intact. - Wernicke's Area: - Involved in language and comprehension - Damage causes Wernicke's aphasia, resulting in fluent but nonsensical speech. What Is amnesia? Amnesia is memory loss, which reveals that there are separate systems for short term memory and long-term memory in the brain. What parts of the brain play a role in memory storage? - Cerebral Hemispheres - Left hemisphere: Involved in storing verbal memory - Right hemisphere: Involved in storing visuospatial memory. What type of memories do the amygdala and hippocampus store? - Amygdala: Crucial for storing fear memories - Hippocampus: Critical for acquiring new memories and consolidating short term into long term memories. Describe the difference between short term and long-term memories? - Short term memories - Function: Holds a small amount of information for a short time (seconds) - Capacity: about 7 elements (ex. phone number) - Location: Primarily in the prefrontal cortex - Long term memories - Function: Stores memory seemingly indefinitely and has unlimited capacity - Involves: Long term potential (LTP), neuronal plasticity, and changes in neural pathways for improves synaptic transmissions What is neuronal plasticity? - Means changes in neurons - Frequently used neural pathways have improved synaptic transmission, making them efficient - Thus, stronger and more efficient neural pathways **Spinal Cord** What is the spinal cord? - Provides two way to/form brain contains spinal reflex centers - Acts as the highway of the central nervous system, connecting the brain with the PNS - Provides two-way communication - Ascending tracts carry sensory information to the brain - Descending tracts carry motor instructions from the brain to effectors. - Mediates spinal reflexes, enabling rapid, automatic responses to stimuli Where does the spinal cord start and end? - Starts at the foramen magnum of skull - Ends at the conus medullaris (medullary cone), located at the fist lumbar vertebra Cross section of spinal cord What parts of neurons are located in the horns, the roots, and the dorsal root ganglion? - Posterior (Dorsal) horns - Dendrites and cell bodies of interneurons (site of sensory neurons synapse) - Anterior (Ventral) horns - Dendrites and cell bodies of lower motor neurons (site of synapse with interneurons or upper motor neurons) - Dorsal Root - Axons of sensory neurons (carry info into the spinal cord) - Ventral Root - Axons of motor neurons (carry signals to effectors) - Dorsal Root ganglion - Cell bodies of sensory neurons (pseudounipolar, located lateral to the vertebral column) How information comes in and out of Spinal Cord 1. Sensory Input - A receptor (pacinian corpuscle) Detects a stimulus and fires an action potential - The action potential travels along the sensory axon of pseudounipolar sensory neuron. 2. Dorsal root ganglion - The sensory neurons cell body is located in the dorsal root ganglion 3. Dorsal Root - The action potential continues through the dorsal root into the spinal cord 4. Interneuron Synapse - The signal may synapse on the interneuron in the posterior (dorsal) horn. - Depending on the pathway, there interneuron may transmit the signal to the brain (via ascending tracts) or directly to a motor neuron. 5. Motor output - The motor neuron in the anterior (ventral) horn sends an action potential - The action potential exists the spinal cord via ventral root 6. Effector response - The signal travels to an effector (muscle or gland), triggering a response (muscle contractions or glans secretion). **PNS: Sensory Division** What part make up the peripheral Nervous system? 1. Components of the PNS: - Neural Structures Outside the Brain & Spinal Cord: - Sensory Receptors: Detect stimuli (internal and external). - Peripheral Nerves & Ganglia: Carry sensory and motor info. - Motor Endings: Connect motor neurons to muscles/glands. 2. Divisions of the PNS: - Somatic Nervous System (SNS): Controls voluntary movement (skeletal muscles). - Autonomic Nervous System (ANS): Regulates involuntary functions. - Sympathetic NS: \"Fight or flight\" response. - Parasympathetic NS: \"Rest and digest\" response. 3. Receptors: - By Stimulus Type: - Mechanoreceptors: Touch, pressure, vibration, stretch. - Photoreceptors: Light. - Thermoreceptors: Temperature changes. - Chemoreceptors: Chemicals. - Nociceptors: Pain. - By Location: - Exteroreceptors: External stimuli (skin, special senses). - Interoceptors: Internal stimuli (viscera, blood vessels). - Proprioceptors: Body position (muscles, tendons, joints). - By Structural Complexity: - Unencapsulated: - Thermoreceptors: Cold (superficial dermis), Heat (deeper dermis). - Nociceptors: Pinching, tissue damage, extreme temps. - Light Touch: Tactile discs, hair follicle receptors. - Encapsulated (Mechanoreceptors): - Meissner's Corpuscles: Discriminative touch. - Pacinian Corpuscles: Deep pressure, vibration. - Ruffini Endings: Continuous pressure. - Muscle Spindles: Muscle stretch. - Golgi Tendon Organs: Tendon stretch. - Joint Kinesthetic Receptors: Joint stretch. What are three ways that sensory receptors can be classified? 1. By Stimulus Type: - Mechanoreceptors - Photoreceptors - Thermoreceptors - Chemoreceptors - Nociceptors 2. By Location: - Exteroreceptors (external stimuli) - Interoceptors (internal stimuli) - Proprioceptors (body position and movement) 3. By Structural Complexity: - Unencapsulated dendritic endings - Encapsulated dendritic endings What stimuli do the following sensory receptors respond to: Mechanoreceptors, photoreceptors, thermoreceptors, chemoreceptors, Nociceptors 1. Mechanoreceptors: Respond to touch, pressure, vibration, stretch, and itch. 2. Photoreceptors: Respond to light energy. 3. Thermoreceptors: Sensitive to changes in temperature. 4. Chemoreceptors: Respond to chemicals. 5. Nociceptors: Sensitive to pain-causing stimuli. Where do the following sensory receptors detect stimuli from (list an example of each): Exteroreceptors, Interoceptors, Proprioceptors 1. Exteroreceptors: - Detect stimuli from outside the body. - Example: Receptors in the skin for touch, pressure, pain, and temperature. 2. Interoceptors: - Detect stimuli from internal viscera and blood vessels. - Example: Sensitive to chemical changes, tissue stretch, and temperature changes within internal organs. 3. Proprioceptors: - Detect stimuli related to body position and movement. - Example: Receptors in muscles, tendons, joints, and ligaments that inform the brain of body movements. What do complex and simple receptors sense? - Complex Receptors: - Sense special senses such as vision, hearing, equilibrium, smell, and taste. - Simple Receptors: - Sense general sensations such as tactile sensations, temperature, pain, and muscle sense. - Unencapsulated Dendritic Endings: - Structure: Do not have a connective tissue capsule surrounding them. - Examples: - Thermoreceptors: Cold receptors (superficial dermis) and heat receptors (deeper dermis). - Nociceptors: Respond to pinching, chemicals from tissue damage, and extreme temperatures. - Light Touch Receptors: Tactile discs and hair follicle receptors. - Encapsulated Dendritic Endings: - Structure: Surrounded by connective tissue capsules. - Examples: - Meissner's Corpuscles: Discriminative touch. - Pacinian Corpuscles: Deep pressure and vibration. - Ruffini Endings: Deep continuous pressure. - Muscle Spindles: Muscle stretch. - Golgi Tendon Organs: Stretch in tendons. - Joint Kinesthetic Receptors: Stretch in articular capsules. Is the ANS sensory or motor? What parts of the body does it innervate?\ The ANS is a motor system responsible for regulating involuntary functions by innervating: - Smooth muscle (e.g., in blood vessels and the gastrointestinal tract) - Cardiac muscle (e.g., the heart) - Glands (e.g., salivary glands, adrenal glands)\ It controls visceral functions such as heart rate, digestion, respiratory rate, and glandular secretion. In somatic motor pathways and autonomic motor pathways, is one motor neuron used or are two used? - Somatic motor pathways: Use one motor neuron that directly connects the CNS to the skeletal muscle. - Autonomic motor pathways: Use two motor neurons: - Preganglionic neuron: Extends from the CNS to an autonomic ganglion. - Postganglionic neuron: Extends from the autonomic ganglion to the target organ. Where are preganglionic and postganglionic cell bodies located? - Preganglionic cell bodies: Located in the CNS (either in the brainstem or spinal cord). - Postganglionic cell bodies: Located in autonomic ganglia outside the CNS. These ganglia can be close to the spinal cord (sympathetic ganglia) or near/within the target organ (parasympathetic ganglia). Describe an autonomic motor reflex and its components: Example: Regulation of blood pressure (Baroreceptor Reflex) 1. Visceral organ: Arteries (detect changes in blood pressure). 2. Sensory receptor: Baroreceptors in the carotid sinus and aortic arch sense stretch (due to pressure). 3. Sensory neuron: Transmits information to the CNS via the glossopharyngeal (CN IX) or vagus (CN X) nerves. 4. Spinal cord: Integrates the sensory input. In some cases, this process involves brainstem centers like the medulla oblongata. 5. Interneuron: Connects the sensory input to the preganglionic neuron in the spinal cord or brainstem. 6. Preganglionic neuron: Transmits the signal to an autonomic ganglion (e.g., sympathetic chain ganglion or parasympathetic ganglion). 7. Postganglionic neuron: Relays the signal to the target organ (e.g., smooth muscle in the arteries or the heart). 8. Visceral organ: Executes the response (e.g., vasoconstriction or dilation to adjust blood pressure). What information does each component of the reflex arc carry/send? - Visceral organ: Produces sensory input based on internal stimuli (e.g., stretch, chemical changes). - Sensory receptor: Detects specific changes in the internal environment (e.g., pressure, pH, oxygen levels). - Sensory neuron: Sends afferent signals from the receptor to the CNS. - Spinal cord: Processes the information and coordinates the response. - Interneuron: Acts as a relay point for sensory and motor integration. - Preganglionic neuron: Carries efferent signals from the CNS to the autonomic ganglion. - Postganglionic neuron: Sends efferent signals to the target visceral organ. - Visceral organ: Implements the motor response (e.g., muscle contraction, secretion, or relaxation). **Sympathetic vs Parasympathetic Nervous System** Pathways (Draw this in your notes) Sympathetic Pathway (SNS) - Preganglionic Neuron: - Short axon (CNS → ganglion near spinal cord). - Releases ACh, binds to Nicotinic receptors on the postganglionic neuron. - Postganglionic Neuron: - Long axon (ganglion → effector organ). - Releases NE, binds to Adrenergic receptors (alpha or beta) on the target organ. - *Exception*: Some pathways (e.g., sweat glands) release ACh → Muscarinic receptors. - Ganglion Location: Near the spinal cord. Parasympathetic Pathway (PSNS) - Preganglionic Neuron: - Long axon (CNS → ganglion near or within target organ). - Releases ACh, binds to Nicotinic receptors on the postganglionic neuron. - Postganglionic Neuron: - Short axon (ganglion → effector organ). - Releases ACh, binds to Muscarinic receptors on the target organ. - Ganglion Location: Near or inside the target organ. **Parasympathetic Nervous System (PNS)** Key Locations and Cranial Nerves - Regions of the Spinal Cord: - PNS nerves originate from the craniosacral regions (brainstem and sacral spinal cord). - Cranial Nerves Involved in PNS: 1. CN III (Oculomotor): Innervates the eye; constricts the pupil and controls lens shape for near vision. 2. CN VII (Facial): Stimulates lacrimal (tear) glands, nasal glands, and salivary glands. 3. CN IX (Glossopharyngeal): Stimulates the parotid salivary gland. 4. CN X (Vagus): Innervates the heart, lungs, liver, stomach, intestines, pancreas, and kidneys; slows heart rate, promotes digestion, and regulates visceral organ activity. - Sacral Nerves: - Innervate the bladder, rectum, and reproductive organs. - Effects: Promote urination, defecation, and sexual arousal (e.g., erection). Cholinergic Fibers: - Definition: Neurons that release acetylcholine (ACh). - Found in both preganglionic and postganglionic neurons of the PNS. Sympathetic Nervous System (SNS) Sympathetic Trunk (Paravertebral Ganglionic Chain): - A chain of interconnected ganglia located on either side of the vertebral column. - Serves as a relay station for SNS pre- and postganglionic neurons. Preganglionic Neuron Cell Bodies Location: - Found in the lateral gray horn of the thoracolumbar spinal cord (T1-L2). SNS Pathway from Spinal Cord: 1. Preganglionic Neuron Cell Body: Located in the lateral gray horn. 2. Preganglionic Neuron Axon: Exits the spinal cord through the ventral root. 3. Enters the white ramus to reach the sympathetic trunk. 4. Synapses with the postganglionic neuron cell body in the sympathetic trunk or collateral ganglion. 5. Postganglionic Neuron Axon: Exits through the gray ramus to reach the target organ. Collateral Sympathetic Ganglia: - Ganglia located outside the sympathetic trunk, including: - Celiac Ganglion - Superior Mesenteric Ganglion - Inferior Mesenteric Ganglion - Postganglionic fibers innervate organs like the stomach, intestines, and kidneys. Adrenal Medulla: - A modified collateral ganglion. - Contains chromaffin cells (modified postganglionic neurons). - Secretes 85% epinephrine and 15% norepinephrine directly into the bloodstream. Mass Activation: - Widespread activation of the SNS through divergence and convergence of pre- and postganglionic neurons. - Necessary for a coordinated \"fight or flight\" response, allowing rapid mobilization of energy. Adrenergic Fibers: - Neurons that release norepinephrine (NE) or epinephrine (Epi). - Found in postganglionic neurons of the SNS and the adrenal medulla. Neurotransmitter Classification: - \*\*SNS Preg Parasympathetic Nervous System (PNS) What regions of the spinal cord are parasympathetic nerves located in? - PNS nerves originate in the craniosacral regions: - Cranial: Brainstem (cranial nerves III, VII, IX, X). - Sacral: Sacral spinal cord (S2-S4). What cranial nerves are part of the parasympathetic nervous system? What organs do they innervate, and what are their effects? - Cranial Nerve III (Oculomotor): - Organ: Eyes. - Effect: Constricts pupils and adjusts lens for near vision. - Cranial Nerve VII (Facial): - Organs: Lacrimal (tear) glands, nasal glands, salivary glands. - Effect: Increases secretion. - Cranial Nerve IX (Glossopharyngeal): - Organ: Parotid salivary gland. - Effect: Promotes salivation. - Cranial Nerve X (Vagus): - Organs: Heart, lungs, liver, stomach, intestines, pancreas, kidneys. - Effects: Slows heart rate, promotes digestion, and regulates visceral organ activity. What do the sacral nerves innervate? What are their effects? - Organs: Bladder, rectum, reproductive organs. - Effects: Promote urination, defecation, and sexual arousal (e.g., erection). What are cholinergic fibers? - Neurons that release acetylcholine (ACh). - Found in preganglionic and postganglionic neurons of the PNS. Sympathetic Nervous System (SNS) What is the sympathetic trunk (AKA paravertebral ganglionic chain)? - A chain of ganglia located on either side of the vertebral column. - Serves as a relay station for pre- and postganglionic neurons of the SNS. Where in the spinal cord are the cell bodies of the preganglionic neurons of the sympathetic nervous system? - In the lateral gray horn of the spinal cord from T1 to L2 (thoracolumbar region). Describe the pathway out of the spinal cord in the SNS using the following terms: - Preganglionic neuron cell body: Located in the lateral gray horn. - Preganglionic neuron axon: Exits via the ventral root. - Passes through the white ramus to reach the sympathetic trunk. - Synapses with the postganglionic neuron cell body in the sympathetic trunk (or collateral ganglion). - Postganglionic neuron axon: Exits through the gray ramus and travels to the target organ. What are collateral sympathetic ganglia? - Ganglia outside the sympathetic trunk that serve abdominal and pelvic organs. Examples: - Celiac ganglion (stomach, liver, kidneys). - Superior and inferior mesenteric ganglia (intestines, urinary bladder). What is the adrenal medulla? What does it produce? - A modified ganglion of the SNS located on the adrenal gland. - Produces and releases epinephrine (85%) and norepinephrine (15%) into the bloodstream. What is mass activation? Why is this necessary in a fight or flight response? - Mass activation is the widespread stimulation of nearly all SNS postganglionic neurons. - Necessary for a coordinated response to danger, allowing: - Increased heart rate. - Redirected blood flow to muscles. - Mobilization of glucose for energy. What are adrenergic fibers? - Neurons that release norepinephrine (NE) or epinephrine (Epi). - Found in SNS postganglionic neurons and the adrenal medulla. Are SNS preganglionic neurons cholinergic or adrenergic? - Cholinergic (release ACh). Are SNS postganglionic neurons cholinergic or adrenergic? - Adrenergic (release NE or Epi). What type of adrenergic receptor does norepinephrine prefer to bind to? - Alpha-adrenergic receptors. What type of adrenergic receptor does epinephrine prefer to bind to? - Beta-adrenergic receptors. What are the antagonists of adrenergic receptors? - Alpha-blockers: Block alpha receptors (e.g., for hypertension). - Beta-blockers: Block beta receptors (e.g., for heart disease). What organs are affected by the SNS? What is the result on these organs? - Eyes: Dilates pupils (alpha1). - Heart: Increases heart rate and force of contraction (beta1). - Lungs: Dilates bronchioles (beta2). - GI tract: Decreases digestion (beta2). - Liver: Increases glucose release into the blood (beta2, alpha1). - Blood vessels: Constricts or dilates depending on receptor subtype. - Sweat glands: Increases sweat production. - Adrenal glands: Secretes epinephrine and norepinephrine. Dual Innervation of the ANS What is dual innervation? - Most organs receive input from both the parasympathetic and sympathetic divisions, which generally have opposite effects. What are examples of antagonistic actions of dual innervation? - Heart: - SNS: Increases heart rate. - PNS: Decreases heart rate. - GI Tract: - SNS: Decreases digestion and motility. - PNS: Increases digestion and motility. - Pupils: - SNS: Dilates pupils. - PNS: Constricts pupils. What are examples of cooperative actions of dual innervation? - Reproductive Organs: - PNS: Promotes erection via vasodilation. - SNS: Promotes ejaculation in males and vaginal contraction in females. What are exceptions to dual innervation? - Organs regulated solely by the SNS: - Adrenal medulla. - Sweat glands. - Most blood vessels. - Arrector pili muscles (causing goosebumps). Control of the ANS by the CNS Which CNS regions influence the ANS? - Medulla Oblongata: Controls heart rate, respiration, blood pressure, and digestion. - Hypothalamus: Major integration center for ANS; regulates body temperature, hunger, thirst, and emotional responses. - Limbic System: Links emotions to ANS responses (e.g., fear causing increased heart rate). - Cerebral Cortex: Limited control; can influence ANS through biofeedback and conscious relaxation techniques. What is the role of the hypothalamus in ANS regulation? - Coordinates sympathetic and parasympathetic responses. - Mediates autonomic responses based on input (e.g., stress triggers fight-or-flight via the SNS). Neurotransmitters and Receptors What are cholinergic receptors? - Receptors that respond to acetylcholine (ACh). - Two types: - Nicotinic Receptors: Found on postganglionic neurons (always excitatory). - Muscarinic Receptors: Found on target organs (can be excitatory or inhibitory). What are adrenergic receptors? - Receptors that respond to norepinephrine (NE) or epinephrine (Epi). - Two main types: - Alpha receptors (α): - α1: Constriction of blood vessels. - α2: Inhibits NE release (negative feedback). - Beta receptors (β): - β1: Increases heart rate and force. - β2: Dilates bronchioles and blood vessels in skeletal muscle. - β3: Stimulates lipolysis in fat cells. What determines the effect of a neurotransmitter? - The type of receptor on the target organ determines whether the response is excitatory or inhibitory. What neurotransmitters do the SNS and PNS use? - SNS: - Preganglionic: Acetylcholine (ACh). - Postganglionic: Norepinephrine (NE) or epinephrine (Epi). - PNS: - Both preganglionic and postganglionic neurons release acetylcholine (ACh). What is the difference between nicotinic and muscarinic receptors? - Nicotinic Receptors: Found on postganglionic neurons; always excitatory. - Muscarinic Receptors: Found on target organs; can be excitatory (e.g., GI tract) or inhibitory (e.g., heart). SNS and PNS Pathway Summaries Sympathetic Nervous System Pathway: - Preganglionic neurons: Short axons release ACh → nicotinic receptors on postganglionic neurons. - Postganglionic neurons: Long axons release NE/Epi → adrenergic receptors on target organs. - Exceptions: Sweat glands and arrector pili use ACh at muscarinic receptors. Parasympathetic Nervous System Pathway: - Preganglionic neurons: Long axons release ACh → nicotinic receptors on postganglionic neurons. - Postganglionic neurons: Short axons release ACh → muscarinic receptors on target organs. Dual Innervation What is dual innervation? - Dual innervation means most organs receive signals from both the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS), often with opposing effects. Antagonistic vs. Cooperative Actions Difference Between Antagonistic and Cooperative Actions: - Antagonistic Actions: - The two divisions oppose each other. - Examples: - Heart: - SNS: Increases heart rate. - PNS: Decreases heart rate. - Pupil: - SNS: Dilates pupils. - PNS: Constricts pupils. - Cooperative Actions: - Both divisions work together for a unified function. - Example: - Reproductive Organs: - PNS: Promotes erection (vasodilation). - SNS: Promotes ejaculation or vaginal contraction. Organs Without Dual Innervation What organs lack dual innervation? - These are regulated solely by the SNS: - Adrenal medulla. - Sweat glands. - Most blood vessels. - Arrector pili muscles. Regulation of Singly Innervated Organs How are singly innervated organs regulated? - By increasing or decreasing the firing rate of sympathetic neurons. - Example: - Blood vessels constrict when SNS firing increases. - Blood vessels dilate when SNS firing decreases. Control of the Autonomic Nervous System 1. Higher Brain Functions: - Cerebral cortex: Voluntary control, emotions, and decision-making. - Cerebellum: Coordinates motor functions and balance. Influence of CNS Regions on the ANS 2. Medulla Oblongata: - Direct control of ANS activity. - Regulates cardiovascular functions (heart rate, blood pressure), respiratory rhythm, and digestive processes. 3. Hypothalamus: - Master control center for the ANS. - Integrates signals for temperature regulation, hunger, thirst, and stress responses. - Relays commands to the medulla for execution. 4. Limbic System: - Links emotions to visceral responses. - Examples: - Stress: Increases heart rate. - Fear: Triggers sweating or a racing heart. 5. Cerebral Cortex and Cerebellum: - Cerebral cortex: Limited conscious control over the ANS (e.g., meditation). - Cerebellum: Fine-tunes ANS responses linked to posture and movement (e.g., adjusting blood flow during exercise).